I don't think there is ONE limiting factor with a cheap machine that purports to make espresso; there are many. It's a bit like trying to use a tricycle on a 10 mile ride; even if you get to the destination, it wasn't worth the effort.
Making good espresso at home takes serious equipment and serious effort. But as I said, not everyone who loves coffee needs to make espresso at home, as there are quite a few other ways to prepare coffee that don't have the same requirements.
I spend several weeks every year visiting my parents and staying in their home. I do have a decent grinder there (nothing special, a Solis, but it works) and use it to make either Melita cone coffee or coffee made with a $25 Aeropress from Amazon.com. I use freshly home roasted coffee that I carry along on those trips.
Although I prefer espresso, I don't find it to be any great sacrifice to have to drink drip when the circumstances don't justify making espresso. And good drip beats bad espresso any day. And don't even ask me about the two months I spend in France each year, where some of the "best" coffee I can find is in French McDonalds.
ken




